Suspension or vertical filing systems designed for use with suspension filing systems are known in the art. For example, U.S. Pat. No. 4,306,736 issued to Cournover et al. on Dec. 22, 1981 discloses a document holder for use with a single rail suspension filing system. Other types of document binders for use with either one rail or two rail suspension filing systems are also known in the art. For example, U.S. Pat. No. 4,171,854 issued to Hedstrom et al. on Oct. 23, 1979; U.S. Pat. No. 4,056,296 issued to Hedstrom et al. on Nov. 1, 1977; and U.S. Pat. No. 3,980,360 issued to Wright et al. on Sep. 14, 1976 each disclose document binders for use with either single rail or double rail suspension filing systems. More specifically, each of these binders includes a document holding channel with two non-retractable hooks extending beyond the ends of the channel to suspend the binder from a two rail suspension system. The channel portion of each of these prior art binders further defines another hook section for suspending the document binder from a single rail suspension filing system.
One problem with the document holders having two hooks extending beyond the ends of the binder for use with the double rail suspension filing system is that the hooks interfere with the storage of the documents when the documents in the binders are stored in a box or shelved as a conventional book. To solve this problem, document binders for use with two rail suspension filing systems were designed with retractable hooks, such that the hooks could be retracted in order to store or shelve the binder with the documents bound within the binder. U.S. Pat. No. 4,445,799 issued to Wright et al. on May 1, 1984; U.S. Pat. No. 3,865,445 issued to Dean et al. on Feb. 11, 1975; and U.S. Pat. No. 3,801,175 issued to Giulie on Apr. 2, 1974 each discloses a document binder with retractable hooks for use on a two rail suspension filing system.
However, these document binders of the prior art used with two rail suspension filing systems have substantially planar, relatively thin hooks. As a result, the hooks are prone to breakage when the binders are carelessly inserted into the two rail suspension filing system, or when the hooks are forced into an extended or retracted position. Therefore, a need exists for a document binder for use with a two rail suspension filing system having retractable hooks of increased strength.
Another problem with the prior art binders used with two rail suspension filing systems is that either the binder does not have a planar area to place a label, or else the only location for placing a label is in a position difficult to see once the binder is filed in the two rail suspension filing system. Therefore, a need also exists for a document binder for use with a two rail suspension filing system with a label mounting area located for convenient visibility when the binder is filed in a file drawer.
Still another problem with the prior art is that the cross-sectional area of the spine portion of the binders tends to be relatively thin. As a result, the binders are not as durable as desired. Therefore, a need exists for a document binder for use with a two rail suspension filing system wherein the cross-sectional area of the binder provides increased strength and support for the bound documents.